JDBC的轻量级封装DBUtils开源组件的使用（二）

在开源中国上看到站长的博客，说开源中国是用java+mysql写的，没有用庞大的Hibernate，而是用的DbUtils组件，于是对这个组件产生了兴趣，根据“JDBC的轻量级封装DBUtils开源组件的使用（一）”简单地学习了一下。下面是写的一个Demo:

TestDbUtils.java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.List;
import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
/**
 * @author 张省三
 * E-mail:[email protected]
 * 2013-7-6 下午10:17:32
 */
public class TestDbUtils {
    private static String driverClassName = "com.mysql.jdbc.Driver";
    private static String url = "jdbc:mysql://localhost:3306/liuyanban";
    private static String user = "root";
    private static String password = "fendou";
    private static Connection conn = null;
                  
    //DBCP数据源
    /*public static BasicDataSource setupDataSource(String connectURI) {
        BasicDataSource ds = new BasicDataSource();
        ds.setDriverClassName(driverClassName);
        ds.setUsername(user);
        ds.setPassword(password);
        ds.setUrl(connectURI);
        //ds.setMinIdle(5);
        return ds;
    }*/
    QueryRunner runner = new QueryRunner();
    /**
     * 得到连接方法
     */
    public static void getConn(){
        if(DbUtils.loadDriver(driverClassName)){//加载驱动
            try {
                conn = DriverManager.getConnection(url, user, password);//得到连接
            } catch (SQLException e) {
                System.out.println("连接失败！");
                e.printStackTrace();
            }        
        }
    }
    /**
     * 增、删、改操作方法
     */
    public void update(){
        getConn();//得到连接
        boolean b = false;
        String sql = "insert into user (username,password) values(?,?)";
        try {
            if(runner.update(conn, sql, "xiaofeng","123456") > 0){//如果返回结果大于0,则执行成功
                System.out.println("插入成功！");
                b = true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally{
            try {
                DbUtils.close(conn);//关闭连接
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    //根据主键值查询,因为查询得到的结果只可能有一条记录，所以这里使用BeanListHandler
    BeanHandler bh = null;
    @SuppressWarnings("unchecked")
    /**
     * 查询方法，返回一条记录
     */
    public User select(int userId){
        getConn();
        User user = null;
        String sql = "select *from user where userId = ?";
        bh = new BeanHandler<User>(User.class);//实例化BeanHandler对象
        try {
            user = runner.query(conn, sql, bh, userId);//查询
            System.out.println(user.getUsername()+"---"+user.getPassword());
            return user;
        } catch (SQLException e) {
            System.out.println("查询出错！");
            e.printStackTrace();
        } finally{
            try {
                DbUtils.close(conn);//关闭连接
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return user;
    }
    //返回一个集合，用BeanListHandler类
    BeanListHandler blh = null;
    @SuppressWarnings("unchecked")
    /**
     * 查询方法，返回一个集合
     */
    public List select(){
        getConn();
        List<User> list = null;
        String sql = "select *from user";
        blh = new BeanListHandler<User>(User.class);//实例化BeanListHandler对象
        try {
            list = runner.query(conn, sql, blh);//查询，返回List
            for(User user : list){
                System.out.println(user.getUsername()+"---"+user.getPassword());
            }
            return list;
        } catch (SQLException e) {
            System.out.println("查询出错！");
            e.printStackTrace();
        } finally{
            try {
                DbUtils.close(conn);//关闭连接
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return list;
    }
    public static void main(String[] args) {
        //new TestDbUtils().update();
        //new TestDbUtils().select(1);
        new TestDbUtils().select();
    }
}

User.java

/**
 * @author 张省三
 * E-mail:[email protected]
 * 2013-7-7 上午01:56:49
 */
public class User {
    private String username;
    private String password;
    private String email;
    private int isAdmin;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public int getIsAdmin() {
        return isAdmin;
    }
    public void setIsAdmin(int isAdmin) {
        this.isAdmin = isAdmin;
    }
          
}